According to Machine Evaluation and Engineering, Inc., the principles examined with universal testing machines are elongation and deformation. These machines exert shear, compressive and tensile forces on a test object to determine its strength, malleability and ductility, as well as other related material properties. They also contain a computer that records and interprets data obtained in each experiment.
Machine Evaluation and Engineering, Inc. explains that one of the most common tests performed with universal testing machines is the compression test. During this test, the sample object sits in the machine's jaws. The operator applies gradually increasing compressive forces to the object by manipulating a screw mechanism on the universal testing machine.
Another important function of universal testing machines is tensile testing. During this procedure, the sample object sits in the machine's jaws, and the operator attempts to elongate the sample.
Universal testing machines do not simply demonstrate the failure point of sample objects subjected to various forces. The machines also create detailed charts and graphs that show the load and stress points as measured throughout each experiment. This information helps researchers understand how objects respond to stress and the changes objects incur as a result. For example, data from a tensile test reveals the point of greatest tensile strength, the initial point of deformation, the point of maximum deformation and the point at which the object separates into multiple pieces.